The present invention relates generally to semiconductor device manufacturing, and more particularly, to temporarily adhering a semiconductor wafer to a wafer carrier to secure it during processing steps such as backside grinding, metallization, and chip dicing.
Integrated circuits are typically made by manufacturing semiconductor wafers. Each semiconductor wafer is typically 100 mm, 125 mm, 150 mm, 200 mm, or 300 mm in diameter and can be approximately several hundred microns thick. In some instances, the semiconductor wafer may have to be thinned in order to reveal through-wafer vias (“TWVs”) for subsequent processing and testing steps. When semiconductor wafers are thinned to a thickness of less than about 150 μm, the semiconductor wafer is usually temporarily attached to a wafer carrier, also known as a handle wafer, in order to secure it during manufacture. Once secured, the exposed side (i.e., “backside”) of the semiconductor wafer may be processed using techniques such as grinding, chemical mechanical planarization (CMP), and cleaning. The backside of the semiconductor wafer may then be subjected to a metallization process in which metals such as titanium, chromium, copper, gold, and combinations thereof are deposited. The metallization process usually takes place by sputter deposition in a high vacuum sputter deposition tool chamber. When manufacture and processing of the wafer is completed, chips or die are cut or “diced” from the wafer and may later be mounted into a single chip package or multiple chip package for implementation in a printed circuit board or other applications.
Typically, the semiconductor wafer is attached to the wafer carrier using an adhesive that is coated and cured on the semiconductor wafer. Typically, the adhesive is deposited on a surface of the semiconductor wafer that is not being processed (i.e., “front side”). The wafer carrier, typically a silicon wafer or a glass carrier, is then placed in contact with the adhesive on the front side of the wafer and allowed to bond. Perforated wafer carriers have been increasingly used because they provide more surface area for adhesion than solid carriers and allow for relatively easy de-bonding by providing holes for solvents to contact and dissolve the adhesive.
However, temperatures at which the semiconductor wafers are typically processed may have an adverse affect on commonly used adhesives. During conventional metallization processes, temperatures in the metal deposition tool chamber, as well as on the semiconductor wafer itself, may exceed the temperature at which commonly used adhesives begin to outgas volatile organic compounds (“VOCs”). The temperature at which outgassing occurs may be referred to as the outgas sing temperature (“Tg”). The outgas sing of VOCs and the subsequent condensation of adhesive droplets may cause poor adhesion of the metal to the backside of the semiconductor wafer, resulting in peeling of the metal layer and poor adhesion. In addition, the outgas sing VOCs may result in the contamination of the process chamber. Accordingly, it may be desirable to overcome the deficiencies and limitations described hereinabove.